"In that vast throng are multitudes of the long-lived race that existed before the Flood; men of lofty stature and giant intellect, who, yielding to the control of fallen angels, devoted all their skill and knowledge to the exaltation of themselves; men whose wonderful works of art led the world to idolize their genius, but whose cruelty and evil inventions, defiling the earth and defacing the image of God, caused Him to blot them from the face of His creation. There are kings and generals who conquered nations, valiant men who never lost a battle, proud, ambitious warriors whose approach made kingdoms tremble. In death these experienced no change. As they come up from the grave, they resume the current of their thoughts just where it ceased. They are actuated by the same desire to conquer that ruled them when they fell. GC 664.1"
"There were giants in the earth in those days; and also after that, when the sons of God came in unto the daughters of men, and they bare children to them, the same became mighty men which were of old, men of renown."
Both passages refer to the giants/mighty men before the Flood. EGW elaborates on their characteristics and influence, drawing a clear connection to Genesis 6:4, which mentions the giants and their renown.
"Satan consults with his angels, and then with these kings and conquerors and mighty men. They look upon the strength and numbers on their side, and declare that the army within the city is small in comparison with theirs, and that it can be overcome. They lay their plans to take possession of the riches and glory of the New Jerusalem. All immediately begin to prepare for battle. Skillful artisans construct implements of war. Military leaders, famed for their success, marshal the throngs of warlike men into companies and divisions. GC 664.2"
"And shall go out to deceive the nations which are in the four quarters of the earth, Gog and Magog, to gather them together to battle: the number of whom is as the sand of the sea."
The EGW passage clearly echoes the imagery of Revelation 20:8, particularly the vast number of the attacking army ('as the sand of the sea') and the gathering for battle. The context of a final battle against God's people is also shared.
"At last the order to advance is given, and the countless host moves on—an army such as was never summoned by earthly conquerors, such as the combined forces of all ages since war began on earth could never equal. Satan, the mightiest of warriors, leads the van, and his angels unite their forces for this final struggle. Kings and warriors are in his train, and the multitudes follow in vast companies, each under its appointed leader. With military precision the serried ranks advance over the earth's broken and uneven surface to the City of God. By command of Jesus, the gates of the New Jerusalem are closed, and the armies of Satan surround the city and make ready for the onset. GC 664.3"
"And they went up on the breadth of the earth, and compassed the camp of the saints about, and the beloved city: and fire came down from God out of heaven, and devoured them."
This is a strong thematic parallel. The EGW passage describes the advance of Satan's army to the City of God, mirroring Revelation 20:9's description of the army compassing the camp of the saints and the beloved city.